1. Field of the Invention
The invention relates to a parking assist system for a vehicle, a contactless power transmitting device and a contactless power receiving device and, more, particularly, to a parking assist system that assists a vehicle, which contactlessly receives electric power, in parking.
2. Description of Related Art
In recent years, a technique for contactlessly transmitting or receiving power to or from a device becomes a focus of attention because of less expense in time and effort for connection, or the like. Contactless charging is in practical use for charging a portable device, an electric vehicle, or the like.
Japanese Patent Application publication No. 2008-288889 (JP 2008-288889 A) describes that a coil formed of a combination of a plurality of coil-shaped members is arranged in a center space of a power supply coil or a power receiving coil that is used for charging an electric vehicle, or the like.
Coil units of a plurality of types have been studied for use in a power transmitting unit and a power receiving unit in contactless power supply.
In contactless power supply, a magnetic flux distribution that is generated in a coil unit or a magnetic flux distribution suitable for a coil unit to receive, electric power varies on the basis of a coil shape, a winding method, a magnetic core shape, and the like. When the magnetic flux distributions of a pair of power transmitting portion and power receiving portion are different from each other, it is not possible to efficiently transmit or receive electric power. It is inconvenient that electric power cannot be transmitted or received at all because of a mismatch between the magnetic flux distribution of the power transmitting portion and the magnetic flux distribution of the power receiving portion.
Depending on a combination of coil types of the power transmitting unit and power receiving unit, the transfer efficiency may be higher when there is a positional deviation than when there is no positional deviation. However, if a location to which a vehicle is guided is changed for each coil type, a driver should stop the vehicle at the center of a parking lot or stop the vehicle at a location that slightly deviates from the center of a parking lot, so a parking feeling deteriorates.